不同产量递减方式对气田效益影响研究

首先运用技术经济学的有关原理,结合油藏工程原理的基本知识,建立了气藏储量初始经济产量的评价模型,得到了在不同天然气产量递减方式和不同内部收益率情况下的单井日产量,然后利用这些数据,运用SPSS软件进行了方差分析,得到了调和递减方式下的单井日产量与直线递减和凸型递减方式下的单井日产量有显著性差异的结论。最后通过SPSS软件对内部收益率、单井日产量、产量递减方式的回归,得到调和递减的效益好于指数递减;指数递减好于直线递减;直线递减好于凸型递减;并且单井日产量为气田效益影响的敏感因素的结论,为油气田经济评价方法提供一种思路。     

起重机回转支承故障的预防和控制

回转支承是起重机承载、回转的重要零部件之一,如果其出现故障,不仅会影响起重机正常作业,而且会造成极大的安全风险。该文以起重机回转支承运行原理为入手点,从系统压力不稳、回转制动阀门无法闭合、回转支承旷动等方面对起重机回转支承故障进行了简单的分析,并依据起重机回转支承故障因素,提出了几点起重机回转支承故障预防及控制措施。     

Modeling extended lactations of Holsteins

Modeling extended lactations for the US Holsteins is useful because a majority (>55%) of the cows in the present population produce lactations longer than 305 d. In this study, 9 empirical and mechanistic models were compared for their suitability for modeling 305-d and 999-d lactations of US Holsteins. A pooled data set of 4,266,597 test-day yields from 427,657 (305-d complete) lactation records from the AIPL-USDA database was used for model fitting. The empirical models included Wood (WD), Wilmink (WIL), Rook (RK), monophasic (MONO), diphasic (DIPH), and lactation persistency (LPM) functions; Dijkstra (DJ), Pollott (POL), and new-multiphasic (MULT) models comprised the mechanistic counterparts. Each model was separately tested on 305-d (>280 days in milk) and 999-d (>800 days in milk) lactations for cows in first parity and those in third and greater parities. All models were found to produce a significant fit for all 4 scenarios (2 parity groups and 2 lactation lengths). However, the resulting parameter estimates for the 4 scenarios were different. All models except MONO, DIPH, and LPM yielded residuals with absolute values smaller than 2 kg for the entire period of the 305-d lactations. For the extended lactations, the prediction errors were larger. However, the RK, DJ, POL, and MULT models were able to predict daily yield within a ± 3 kg range for the entire 999-d period. The POL and MULT models (having 6 and 12 parameters, respectively) produced the lowest mean square error and Bayesian information criteria values, although the differences from the other models were small. Conversely, POL and MULT were often associated with poor convergence and highly correlated, unreliable, or biologically atypical parameter estimates. Considering the computational problems of large mechanistic models and the relative predictive ability of the other models, smaller models such as RK, DJ, and WD were recommended as sufficient for modeling extended lactations unless mechanistic details on the extended curves are needed. The recommended models were also satisfactory in describing fat and protein yields of 305-d and 999-d lactations of all parities.     

Feeding strategy, nitrogen cycling, and profitability of dairy farms

On a typical dairy farm today, large amounts of N are imported as feed supplements and fertilizer. If this N is not recycled through crop growth, it can lead to large losses to the atmosphere and ground water. More efficient use of protein feed supplements can potentially reduce the import of N in feeds, excretion of N in manure, and losses to the environment. A simulation study with a dairy farm model (DAFOSYM) illustrated that more efficient feeding and use of protein supplements increased farm profit and reduced N loss from the farm. Compared to soybean meal as the sole protein supplement, use of soybean meal along with a less rumen degradable protein feed reduced volatile N loss by 13 to 34 kg/ha of cropland with a small reduction in N leaching loss (about 1 kg/ha). Using the more expensive but less degradable protein supplement along with soybean meal improved net return by $46 to $69/cow per year, dependent on other management strategies of the farm. Environmental and economic benefits from more efficient supplementation of protein were generally greater with more animals per unit of land, higher milk production, more sandy soils, or a daily manure hauling strategy. Relatively less benefit was obtained when either alfalfa or corn silage was the sole forage on the farm or when relatively high amounts of forage were used in animal rations.     

新疆玛纳斯赤霞珠葡萄生长结果习性调查简报

赤霞珠是北疆地区主栽酿酒葡萄良种,通过对新疆玛纳斯种植的8年生赤霞珠葡萄调查和分析,萌芽率平均为77．6％,成枝率88．2％,结果枝率85．8％,结果系数1．63,表现出较国内其它省区较优的生产结果习性。中结果母枝（3～4节）、短结果母枝（1～2节）的结实能力较长结果母枝（5～6节）强,相同节位芽的结果能力随着结果母枝长度增加而下降。冬季修剪主要应以中、短梢修剪为主,幼龄树可对主蔓进行延长修剪。     

高光谱图像技术定量检测香醋醋醅水分分布均匀性

水分含量是影响镇江香醋醋醅发酵的重要因素,探索醋醅中水分分布均匀性的定量描述方法,可为精确调控香醋发酵工艺提供科学依据。利用高光谱图像技术检测醋醅中水分含量的二维分布图,以水分分布图的标准差作为定量指标,首次提出醋醅水分分布均匀性的定量描述方法。首先利用醋醅高光谱图像信息结合遗传算法建立水分含量检测模型;其次提取各像素点对应的高光谱图像信息代入水分含量检测模型,快速计算出所有像素点对应的水分含量,从而描绘醋醅水分含量二维分布图;最后计算水分含量分布图的标准差,以此定量表征各像素点水分含量与所有像素点水分含量均值之间的离散程度,两者之间离散程度越小,水分分布越均匀。研究表明:高光谱图像技术定量分析醋醅水分分布均匀性是可行的,为定量描述固态发酵关键指标的分布均匀性提供了新的检测手段。     

The evaluation of a PCR-based method for identification of Salmonella enterica serotypes from environmental samples and various food matrices

The most commonly used method for serotyping Salmonella spp. is based on the Kaufmann–White scheme, and is composed of serological reactions using antibodies to LPS agglutinins. The multiplex PCR used in this investigation was established by Kim et al. to serotype the 30 most common clinical Salmonella serotypes, as determined by CDC. The PCR assay consists of two five-plex reactions and a single two-plex PCR reaction, based on six genetic loci from Salmonella enterica serotype Typhimurium and four loci from S. enterica serotype Typhi. In this investigation, we further evaluated the method for serotyping Salmonella spp. using a reference collection, environmental samples collected from a Mid-Atlantic region tomato farm study, four food matrices spiked with different Salmonella serotypes and a proficiency test. The PCR assay was first evaluated using DNA isolated from pure cultures of isolates obtained from various clinical and environmental samples, and then DNA isolated from broth cultures of food matrices of “Red round” and Roma tomatoes, Romaine lettuce, green onions and Serrano peppers spiked with serotypes Newport, Typhimurium, Javiana and Saintpaul, respectively. The results showed that the PCR assay correctly serotyped Salmonella spp. from the clinical, environmental, spiked food matrices, and proficiency test samples. These findings are significant because the PCR assay was successful in the identification of Salmonella in the spiked samples in a broth culture containing other non-salmonella organism. This method may be a useful resource for the food safety community.     

高光谱图像技术检测枇杷叶片三萜酸含量及叶面分布

枇杷叶富含三萜酸类化合物,具有较高的药用价值。本研究首先建立枇杷叶高光谱信号与三萜酸含量的对应关系,然后利用高光谱图像包含每个像素点的光谱信号这一独特优势,检测枇杷叶片的三萜酸分布。通过联合区间偏最小二乘法(si PLS)建立三萜酸含量分析模型,结果表明,采用si PLS将全光谱均匀划分11个子区间,选择1、5、6、7联合,主因子数为4 h,建立的si PLS谱区筛选模型预测效果最佳,其交互验证均方根误差(RMSECV)和预测均方根误差(RMSEP)分别为3.392 mg/g和3.731 mg/g,校正集和预测集相关系数分别为0.8449和0.8223。根据si PLS模型计算叶片上所有像素点处的三萜酸含量,并通过伪彩色方法描述叶片中三萜酸含量的分布。研究结果表明,利用高光谱图像技术分析枇杷叶片三萜酸含量及叶面分布是可行的。     

Effect of cationic flaxseed protein hydrolysate fractions on the in vitro structure and activity of calmodulin-dependent endothelial nitric oxide synthase

The objective of this study was to determine the in vitro effects of cationic flaxseed protein hydrolysate fractions on calmodulin (CaM) structure as well as the activity of CaM-dependent endothelial nitric oxide synthase (eNOS). Flaxseed protein isolate was hydrolyzed with alcalase, and two peptide fractions were isolated by cation-exchange chromatography. Fraction I, eluted first from the column, and fraction II contained 42% and 51% contents of basic amino acids, respectively. Fractions I and II reduced the activity of CaM-dependent eNOS through a mostly mixed-type inhibition mode. Fraction II was at least ten times more effective as an eNOS inhibitor when compared to fraction I, as evident from the IC(50) (concentration of protein hydrolysate that reduced eNOS activity by 50%) values. Fluorescence spectroscopy showed that the tyrosine residues in CaM were increasingly exposed upon addition of fraction I, while the opposite was the case when fraction II was added. Circular dichroism studies showed that fractions I and II reduced the alpha-helix content but increased the rigidity of the active calcium/CaM complex. We concluded that ability of the protein hydrolysate fractions to change the secondary and tertiary structures of CaM may explain their ability to reduce activity of CaM-dependent eNOS.